金属渗碳腐蚀(即尘化)是高温碳氢环境下常发生的灾难性腐蚀.Cr5Mo 钢的工程应用量大面广,过去对其渗碳腐蚀研究不够.为此,研究了炉管材料Cr5Mo钢在600 ℃,50%CO-H_2-3%H_2O气氛下的尘化腐蚀行为,采用X射线衍射分析了腐蚀试样的物相组成,采用扫描电镜对试样进行了微观形貌分析.结果表明:Cr5Mo 钢在试验条件下呈现均匀腐蚀,材料自表面向内依次析出Fe_5C_2和Fe_3C脆性腐蚀产物,经560 h尘化腐蚀后的试样平均腐蚀深度约为200 μm,而基体材料性质无明显改变.因此Cr5Mo 钢在尘化过程中出现的腐蚀减薄是由脆性碳化物层的析出引起的.
The carbonization corrosion (referring to catastrophic corrosion of Fe-based or Ni-hased metals and alloys in high-temperature hydrocarbon atmosphere, also called metal dusting) behavior of heat-furnace tube material Cr5Mo was evaluated in 50%CO-H_2-3% H_2O mixture at 600 ℃. The chemical composition of the corroded samples was analyzed by using an X-ray diffractometer, and the morphology of the corroded samples was observed by using a metallographic microscope and a scanning electron microscope. Results show that Cr5Mo steel has experienced even corrosion under the selected testing conditions, which leads to the formarion of brittle Fe_5C_2 layer and mixed Fe_3 C plus Fe from the exterior surface to internal matrix. The average corrosion depth of the samples after 560-hour metal dusting reached to 200μm, but the properties of the metal matrix were hardly changed. This implies that the deteriorating and corrosion-induced thinning of the Cr5Mo steel during metal dusting are attributed to the precipitation of the brittle carbide layer.
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